The invention relates to the field of microwave tunable devices.
(Ba,Sr)TiO3 (BST), Ni or Mn doped BST, (Ba,Zr)TiO3 (BZT) (Ba,Hf)TiO3 (BHT), SrTiO3 (ST), Bi2(Zn1/3Nb2/3)O7 (BZN) and related thin films are promising materials for tunable microwave devices applications such as electronically tunable mixers, oscillators, and phase shifters and filters. From this point on, when BST is mentioned, it is understood that it is representative of one or more related perovskite-like tunable dielectric materials. These days, the majority of research and development related to ferroelectric thin films for microwave tunable device applications are based on the BST series films grown on single crystal substrates such as MgO, LaAlO3, SrTiO3 and Al2O3. These substrates promote epitaxial growth of the ferroelectric thin films and provide lower substrate loss. To conveniently exploit the advantages of miniaturization and Si process compatibility, it is essential to integrate BST onto Si substrates.